The processes most widely used to date in fabricating magnetic thin films have been vacuum deposition and sputtering. However, a source material having the same composition as the desired magnetic thin film must first be prepared before these processes can be applied. When a change is to be made in the composition of a magnetic thin film, preparation must commence first with the source material, adding the inconvenience that raises production costs. Moreover, when these processes are used, a rather low proportion of atoms and particles leaving the source material are deposited on the substrate. In vacuum deposition in particular, most of the evaporated atoms and particles are lost through deposition onto the walls in the vicinity of the substrate.